With a rapid increase in the amount of information in recent years, there have been demands for considerably larger capacity in information recording devices such as magnetic recording devices. Under the circumstances, hard disk drives (HDD) have always been used as information recording devices in computers due to their overwhelmingly low bit-unit price and high data transfer speed compared to other recording methods.
In recent years, the recording density of hard disks have been achieving an incredible 100% annual increase, and it has been reported that 100 Gb/in2 (15.5 Gb/cm2) was recorded recently on an experimental level.
However, in spite of such circumstances, an even higher density is demanded of hard disk drives' recording density.
Magnetic recording media that are used in hard disk drives generally are disk-shaped, where ring-shaped regions are called tracks. Each track is segmented by a plurality of regions which record tracking servo signals (hereinafter called “tracking servo signal storage regions”). Within a track, regions that are divided by the tracking servo signal storage regions become regions for data signals (hereinafter called “data signal storage regions”).
The movement of a magnetic head for writing or reading data operates as follows: the magnetic head reads servo signals that are recorded in one of the tracking servo signal storage regions, a head actuator is controlled based on the signal, and the magnetic head is moved to a target position.
To record tracking servo signals on a recording medium, a servo writer device is generally used to write tracking servo signals on the recording medium after making the magnetic recording medium.
However, as track width is decreased to increase track density (recording density), advanced control of signal write position becomes required; consequently, the servo writer device must have a mechanism to accurately position itself, which increases the price of the server writer device.
Furthermore, since signals must be written in numerous tracks due to higher track density, more time is required to write tracking servo signals, which increases manufacturing costs.
The reason for having to form tracking servo signal storage regions using a servo writer device that has advanced positioning control after making a magnetic recording medium is that magnetic properties of the data signal storage regions and of the tracking servo signal storage regions are the same.